The present invention relates to a numerical control system, and more particularly to a numerical control system, in which a memory within a numerical control apparatus can be utilized in an effective manner.
A numerical control apparatus (hereinafter, referred to as "NC") reads out machining data in succession and performs predetermined numerical control processing on the basis of the machining data, to thereby machine a workpiece as programmed.
A machining data input method has heretofore been such that a machining program is punched in a paper tape beforehand and that each time the numerical control processing based on the machining data of one block ends, the machining data of the next block is read out by means of a tape reader. Since, however, such a method cannot realize numerical control processing at high speed, a method referred to as "memory operation" has recently come into widespread use. The memory operation is such that a machining program recorded on an external storage medium, e.g., a paper tape, is previously stored in a memory built in the NC, and the machining data is successively read out of the memory at the time of numerical control processing. According to such a memory operation method, a high-speed numerical control processing becomes possible. However, the capacity of the memory must be made large in order to store a long machining program, and this has led to such disadvantages such as high cost, etc.